1
JEE Main 2017 (Online) 9th April Morning Slot
+4
-1
A signal is to be transmitted through a wave of wavelength $$\lambda$$, using a linear antenna. The length l of the antenna and effective power radiated Peff will be given respectively as :

(K is a constant of proportionality)
A
$$\lambda$$, Peff = K $$\left( {{1 \over \lambda }} \right)$$2
B
$${{\lambda \over 8}}$$, Peff = K $$\left( {{1 \over \lambda }} \right)$$
C
$${{\lambda \over 16}}$$, Peff = K $$\left( {{1 \over \lambda }} \right)$$3
D
$${{\lambda \over 5}}$$, Peff = K $$\left( {{1 \over \lambda }} \right)$$$${\left( {{1 \over \lambda }} \right)^{{1 \over 2}}}$$
2
JEE Main 2017 (Online) 8th April Morning Slot
+4
-1 A signal of frequency 20 kHz and peak voltage of 5 Volt is used to modulate a carrier wave of frequency 1.2 MHz and peak voltage 25 Volts. Choose the correct statement.
A
Modulation index = 5, side frequency bands are at 1400 kHz and 1000 kHz
B
Modulation index = 5, side frequency bands are at 21.2 kHz and 18.8 kHz
C
Modulation index = 0.8, side frequency bands are at 1180 kHz and 1220 kHz
D
Modulation index = 0.2, side frequency bands are at 1220 kHz and 1180 kHz
3
JEE Main 2017 (Offline)
+4
-1 In amplitude modulation, sinusoidal carrier frequency used is denoted by $${\omega _c}$$ and the signal frequency is denoted by $${\omega _m}$$. The bandwidth ($$\Delta {\omega _m}$$) of the signal is such that $$\Delta {\omega _m}$$ < < $$\omega _c$$. Which of the following frequencies is not contained in the modulated wave?
A
$${\omega _m}$$
B
$${\omega _c}$$
C
$${\omega _m}$$ + $${\omega _c}$$
D
$${\omega _c}$$ - $${\omega _m}$$
4
JEE Main 2016 (Online) 10th April Morning Slot
+4
-1 A modulated signal Cm(t) has the form Cm(t) = 30 sin 300 $$\pi$$t + 10 (cos 200 $$\pi$$t −cos 400 $$\pi$$t). The carrier frequency c, the modulating frequency (message frequency) f$$\omega$$, and the modulation index $$\mu$$ are respectively given by :
A
fc = 200 Hz; f$$\omega$$ = 50 Hz; $$\mu$$ = $${1 \over 2}$$
B
fc = 150 Hz; f$$\omega$$ = 50 Hz; $$\mu$$ = $${2 \over 3}$$
C
fc = 150 Hz; f$$\omega$$ = 30 Hz; $$\mu$$ = $${1 \over 3}$$
D
fc = 200 Hz; f$$\omega$$ = 30 Hz; $$\mu$$ = $${1 \over 2}$$
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